Enhancing voluntary contributions in a public goods economy via a minimum individual contribution level

We propose and theoretically analyze a measure to encourage greater voluntary contributions to public goods. Our measure is a simple intervention that restricts individuals’ strategy sets by imposing a minimum individual contribution level while still allowing for full free riding for those who do not want to contribute. We show that for a well-chosen value of the minimum individual contribution level, this measure does not incentivize any additional free riding while strictly increasing the total contributions relative to the situation without the minimum contribution level. Our measure is appealing because it is nonintrusive and in line with the principle of “freedom of choice.” It is easily implementable for many different public goods settings where more intrusive measures are less accepted. This approach has been implemented in practice in some applications, such as charities.